FAQs – Improving Energy Efficiency in Chiller Plants
Modern water cooled chillers and chiller plants using properly applied, proven control strategies can have significant improvement in efficiency with out concern for chiller compressor surging, capacity deterioration or excessive chiller starts.
- Will my chiller benefit with the Chiller Plant Optimizer?
- If the strategies employed by the Chiller Plant Optimizer are proven why don’t engineers regularly use them?
- Is oil migration a concern?
- How are compressor surge problems avoided?
- How are excessive chiller starts prevented?
- Can savings be determined before installation of the Chiller Plant Optimizer?
- Can savings be verified after installation?
- Are there competitive alternatives to the Chiller Plant Optimizer?
- How is the Chiller Plant Optimizer differentiated?
- What does ASHRAE say about Chiller Plant Optimization
Yes, all water cooled chiller plants with vapor compression (Carnot Cycle) machines will benefit with the control strategies employed by the Chiller Plant Optimizer. The control strategies are proven technologies and are employed in an open system to improve the energy efficiency of typical chiller plants using constant speed or variable speed chillers.
The patented application method is unique and it is applicable across various chiller platforms, and is compatible with building automation systems. This unique technology is applicable to water cooled chiller plants of all sizes using centrifugal, screw and reciprocating type compressors.
Two year paybacks are possible even with moderately sized 400 ton chillers. Larger chillers will achieve quicker paybacks.
When these strategies are custom designed into most building automation systems the engineer must make a number of design compromises in an attempt to avoid the problems of chiller compressor surging, potential capacity control issues and excessive chiller starts. These compromises significantly limit the savings and many times the cost benefit ratio is not favorable.
When the plant configuration or load pattern changes, and the owner encounters problems with older application methods, he contacts the chiller service expert who has no choice but to disable the strategies.
Typically, engineers find the strategies awkward and complicated to apply, expensive to implement, difficult to commission and maintain.
In other words, before now, these strategies were not available to most chiller plant owners and operators.
Referency 2003 ASHRAE Handbook “HVAC Applications, Chapter 41.
This is no longer a problem of concern for a couple of reasons, 1) Limits if needed for older model chillers are easy to set, 2) newer model chillers don’t have these limits.
The following is a quote from the above ASHRAE reference and can be found on page 41.15 under the subsection titled “Overrides for Equipment Constraints – … ‘Many (older) chillers have a low limit on the condenser water supply temperature that is necessary to avoid lubrication migration from the compressor.
The application method employed by the Chiller Plant Optimizer is fail safe and will avoid a situation that might create compressor stall which leads to surging.
Let’s quickly review underlying cause of compressor surge and the potential conditions that lead to this situation. A compressor surges when the compressed gases (refrigerant gas) flow backward into the compressor. This will happen if the compressor is overloaded, that is if the chiller capacity is insufficient to carry the load. A second cause is high pressure in the condenser as a result extremely high entering condenser water temperature, or extremely low condenser water flow.
Since the Chiller Plant Optimizer is in direct control of condenser water temperature and condenser water flow, it maintains these parameters well out of the range where surge problems will occur. The methods employed by the Chiller Plant Optimizer will not let part load efficiency improvements limit capacity demands when needed by the chiller.
Excessive chiller starts will occur when the 1st chiller has been capacity limited due to a low condenser water temperature and the 2nd has to be operated to meet the plant load requirements. The Chiller Plant Optimizer will not let this condition occur. When the load requirement demands a higher condenser water temperature the Chiller Plant Optimizer immediately adjusts the temperature to meet the operational requirements of the chiller.
With the open application technology used by the Chiller Plant Optimizer, we are able to provide calculations for specific installations that will predict the system performance with and without the chiller plant optimizer, so that one can determine the savings potential of the installation.
In addition the total cost of installation is easily defined up front so that one can easily determine the payback and return on investment potential prior to installation.
The Chiller Plant Optimizer monitors the operation and compares actual results with base line operations with a display showing the immediate results. These results are accumulated over a measure time and readily displayed.
There are several reasons. The Chiller Plant Optimizer is a new product. We think that a comparison to others technologies will help you to recognize the obvious advantages of our product. We also want to encourage you to improve your chiller plant operation, regardless of whose technology you use, because either way the environment is a winner. The more you know about the use of these technologies by others (and especially by a major chiller manufacturer) gives you another tool to evaluate and validate the technology.
It is an offsite pre-configured instrumentation and control packaged that can be installed by any competent mechanical and HVAC contractor. This is possible only with the innovative and patented application method incorporated into the Chiller Plant Optimizer allowing it to be installed as a stand alone control package or interconnected into any existing BAS system for any chiller plant.
As a stand alone package the Chiller Plant Optimizer is a local device that does not depend on “cloud” services. On the other hand several options allow direct access via a local computer browser through a network.
Unlike the Chiller Plant Optimizer, ASHRAE does not define a clear implementation procedure, nor definitive methods for estimating potential savings.
Refer to the 2003 ASHRAE Handbook “HVAC Applications” Chapter 41 titled “Supervisory Control Strategies and Optimization”. Specific details can be found beginning at page 41.12 under the section titled “Supervisory Controls Strategies and Tools – Cooling Tower Fan Control”